1. Field of the Invention
The invention relates to a motor control device for controlling an electric multi-phase brushless d.c. motor having a magnetic rotor and a plurality of windings, the motor control device comprising
a detection unit adapted to generate a commutation signal on the basis of the back-emf voltage produced in the windings, and PA1 an output stage having outputs for the connection of the windings, at least one terminal for the connection of a power-supply source, and a plurality of control elements for selectively coupling the terminal to outputs in dependence upon the commutation signal. PA1 means for recording and/or reproducing information in a cycle, this cycle being in synchronism with a periodic reference signal, PA1 a motor for driving an element which cooperates with said recording and/or reproducing means, PA1 a sensor for detecting the position of said element, said sensor generating a sensor signal, and PA1 a motor control device for controlling the motor. PA1 a phase detector having a first input for receiving a periodic sensor signal related to the instantaneous position of the rotor, and a second input for receiving a periodic reference signal, the detector being adapted to generate a phase-error signal which is representative of the phase difference between the sensor signal and the reference signal, and PA1 a controllable power-supply stage adapted to feed a bidirectional current via the outputs of the output stage in dependence upon the phase-error signal for driving and braking the rotor in a controlled manner. PA1 means for recording and/or reproducing information in a cycle, said cycle being in synchronism with a periodic reference signal, PA1 a motor for driving an element which cooperates with said recording and/or reproducing means, PA1 a sensor for detecting the position of said element, said sensor generating a sensor signal, and PA1 a motor control device in accordance with the invention.
The invention further relates to an apparatus for the recording and/or reproduction of information, comprising
2. Description of the Related Art
Such a motor control device is known from U.S. Pat. No. 4,752,724. The known motor control device comprises a detection unit connected to the windings of a three-phase brushless d.c. motor for detecting the back-emf voltage generated in the windings. On the basis of the detected back-emf voltage, a commutation signal is generated. The known motor control device further has an output stage comprising a plurality of bipolar transistors for selectively coupling the windings to a power source. The transistors are controlled by a signal generator which is controlled by means of the commutation signal. The known motor control device is suitable for energizing the windings of a brushless motor in accordance with a given pattern for which the windings generate such a rotary field that the rotor is constantly driven.